Merge pull request #1 from stuffmc/vast2

VAST 2.0 Support — From what I can tell you only supported VAST 1.x
Merge remote-tracking branch 'stuffmc/vast2'
Fix compile errors
Fix memory leak
Add player item error log
Check if VideoClicks element exists
Including the already contained Impressions in a videoAd — e.g. when we're in an InlineAd which is coming from a Wrapper.
Merge branch 'refs/heads/master' into vast2
Including the already contained clickTrackingURLs in a videoAd — e.g. when we're in an InlineAd which is coming from a Wrapper.
A Wrapper VAST 1 in contrary to a Wrapper VAST 2 or an InLine (VAST 1 or 2) has the <VideoClicks> in its root instead of in the Video Tag.
Tracking impressions before playing — also allows to track impressions of Ads not playing a media file (e.g. Fallback)
Only tracking "start" and "complete" for ads that play media file.